6502 or 65C02?

Talk about your replica, what you have done and what you use it for

6502 or 65C02?

Postby Kallikak » Mar Mon 13, 2006 12:15 am

Hi,

My replica 1 has a 65C02 CPU, and I was wondering if they all did? If you've read another thread by me in the software section, you'll know I've been writing an assembler. The parser and object code-generation is essentially done now, but I still need to write a little command shell for editing and assembling, but progress is good. Currently the assembler only knows the 6502 opcodes, but if all the replicas have a 65C02, I'll consider extending it. Certainly there are some useful additional instructions in the 65C02, and one important bug fix! :-)

I've just gotten the parts to build Vince's little EEPROM burner, and so I plan to burn myself a ROM containing the Woz monitor, Integer BASIC, the Apple disassembler, and my assembler (I have 3K space, and it currently needs 1.5K, so looking good).

I also put in a non-volatile RAM chip on the weekend - very cool. :-)

Ken
Kallikak
 
Posts: 172
Joined: Jan Sun 29, 2006 6:42 pm
Location: Sydney

Postby seventeen » Mar Mon 13, 2006 5:14 pm

Hi Ken,
My replica has a 65C02...
Regards,
Andy.
seventeen
 
Posts: 1
Joined: Nov Tue 15, 2005 8:40 pm
Location: Scotland

Postby vbriel » Mar Mon 13, 2006 10:30 pm

99% of the replica 1's have 65c02's in them. I came across a batch of NOS 6502's and accidently used them in orders :( They were date coded 82 and I still kick myself for sending those out.

I like to write code that is compatible with both the Apple 1 and the replica but that is almost impossible with a program of any real size because of the Apple 1's 8K of RAM. You should be safe with the extended C02 code.

Vince
User avatar
vbriel
Site Admin
 
Posts: 1184
Joined: Jul Tue 19, 2005 12:10 pm
Location: Ohio

Postby cheese1113 » Mar Wed 15, 2006 6:12 pm

I have a regular 6502 on mine.
Max Wooden
cheese1113
 
Posts: 92
Joined: Nov Sun 13, 2005 1:49 am
Location: CA

Postby programsynthesiser » Mar Wed 29, 2006 8:49 pm

What is wrong with the older 6502's? I found this old white 6502 with a gold core looking thing on top, my guess dated in the late 70's or early 80's. It seems to run fine, it just does not display an annoying character in addition to the first / on startup, just a /. This because of a change in newer 6502's? But there is no initial /, I must press reset to get one. Not like I care, that old chip is really cool!

But I still have my original one as backup.
It works!
programsynthesiser
 
Posts: 28
Joined: Oct Sun 02, 2005 1:39 pm
Location: CA

Postby Kallikak » Mar Wed 29, 2006 9:37 pm

Nothing is particularly "wrong" with it, but there are some problems and shortcomings.

Have a look here for a discussion: http://www.strotmann.de/twiki/bin/view/APG/AsmCpuBugs

Personally, I have stuck to using pure 6502 for coding my assembler so it will also run on Apple IIe's and earlier. Also, it only generates code for a 6502. Expanding it is not straightforward since it only just fits inside the 4 KB of ROM it needs to share with the Apple disassembler and the monitor. :)

Ken

Edit: There are some formatting mistakes in the link above. See here instead: http://www.textfiles.com/programming/6502bugs.txt
Kallikak
 
Posts: 172
Joined: Jan Sun 29, 2006 6:42 pm
Location: Sydney

Postby programsynthesiser » Mar Thu 30, 2006 10:13 pm

I meant the difference between pure 6502's now, and mine from the late 70's. 65c02? That's reserved for the IIc. ;)
It works!
programsynthesiser
 
Posts: 28
Joined: Oct Sun 02, 2005 1:39 pm
Location: CA

Postby Kallikak » Apr Sat 01, 2006 4:55 am

The only thing I'm aware of is the absence of the ROR instruction in the earliest ones.
Kallikak
 
Posts: 172
Joined: Jan Sun 29, 2006 6:42 pm
Location: Sydney

Postby programsynthesiser » Apr Sat 01, 2006 4:41 pm

Ah, very good then. The ironic part about all this is that now I am stuck with the old 6502, because I accidentally left my 65c02 out and it was stolen yesterday. :P

Works out for my retro side, doesn't it? :D
It works!
programsynthesiser
 
Posts: 28
Joined: Oct Sun 02, 2005 1:39 pm
Location: CA


Return to replica 1 General Discussion

Who is online

Users browsing this forum: No registered users and 3 guests

cron